Screen human serum samples against a large well defined cell panel to detect the presence of alloantibodies directed against currently unidentified polymorphic non-MHC antigens. Tissue distribution is to be determined by utilizing multiple cell types, and non-MHC linkage is to be determined by testing sera of interest in well characterized families. Reagents discovered by these efforts are to be supplied to the NIAID in amounts not less than 50 ml.